Sling Meister

Went to pull my lower timing gear off with a puller. Wasn’t paying atttention and ended up cross threading like the first 6 or so threads. How should I go about tapping it or should I just get a new crank. It’s from a 350
the gear puller was a different thread

Aaron R.

Seems like you don't have much to lose by retapping it. I would also measure how deep the bolt reaches afterward and maybe buy the longest bolt you can fit before it bottoms out in the crank. A tap will reshape those buggered up threads, but there will be metal missing and you want max thread available for the bolt now.

sofakingdom

iTrader: (1)

You can try tapping it, sometimes that works. Especially if you can get the tap to follow the original threads.

If not, just Heli-Coil it.

Sling Meister

If I tap it do I go by the original bolt size or do I go a size over

sofakingdom

iTrader: (1)

Original

7/16"-14 (std thread) if memory serves.

DO NOT UNDER ANY CIRCUMSTANCES sodomize your crank by forcing some other thread in there.

Sling Meister

What does std thread mean

dbrochard

iTrader: (3)

standard thread
Make sure you use a specific tapping oil or wd40 on the tap too

Sling Meister

I bought a new Timing set do I honestly need to put the new lower gear on or can I just use the old one and just skip having to take it off

GeneralDisorder

iTrader: (1)

You should definitely replace that gear.

You can drill and tap the crank to the Chevy BB size. I have a '70 block in my Jimmy that this was apparently already done to when I got it (no clue why but seems likely that there was some kind of thread malfunctory). Found this out when I swapped balancers, etc. That engine makes about 350 HP with a cam and vortec heads so it doesn't seem to be any issue with upping the bolt size.

GD

J.C. Denton

iTrader: (1)

Well... You should DEFINITELY replace it.. Just sayin'...